Hi everybody,
I'm interested in building a Nom Nom that allows me to control the speed with my foot. I figure I'd ask a few questions before I did something stupid:
1) Is it even possible to put a Nom Nom in a wah? The "speed" control on the build diagram calls for a 500kC pot, but I can't find any wah pots in that value (I checked Smallbear & Mammoth)
2) Is there anything else I need to consider?
I just saw this last night so it should just be a matter of finding the correct wah pot.
http://www.musiciansfriend.com/amplifiers-effects/mxr-csp-001x-variphase-pedal
Another option could be to convert the wah to control an LED/LDR combo. It might take some experimenting to get the sweep right but I think it could be done. I have done it with a standard wah. Look for RG Keens "Technology of the Wah" He has a schematic for making the wah pedal remote. You can use that principle but still inside the same enclosure.
Actually I just remembered that the enclosure I used had a 500k pot in it. Probably not 500kC but close enough. What you want is a dunlop high gain volume pedal. It's not a boost or anything, just a pot in a wah shell, a great starting point for building something else into.
Okay, I did more digging and had a few more questions:
Could I put one of these pinion gears on top of this specific 500kC pot?
Pinion gear:
http://smallbear-electronics.mybigcommerce.com/pinion-gear-for-knurled-shaft/
Long shaft 500kC pot:
http://www.mouser.com/ProductDetail/Alpha-Taiwan/RV16AF-10-15K-C500K-3/?qs=sGAEpiMZZMukHu%252bjC5l7YS%252bP%2fOmpcJEdDFifXFBDggY%3d
Could that type of pot handle the multiple rotations in a wah?
The data sheet on the pot, said the ones with a switch were rated at 15,000 rotations. I am assuming the ones without switches are the same, but the hot potz II is rated for 1 million rotations. so it may work for a period of time but you will likely see failure at some point.
The other thing to take into consideration is that a wah doesn't use the full rotation of the pot so it may work better with the 500K wah pot because everything is bunched up at the end of the rotation.
Are there 500kA wah pots? You could reverse the action.
OR - use a 250kA pot and modify the LFO for slower speeds!
http://smallbear-electronics.mybigcommerce.com/wah-pots-joe-gagan-specials/
There is a 500k but it is an ICAR like taper. But from the charts I have seen the icar starts like an audio with a linear midsection and finishes like a reverse audio.
this one from the gear page makes it look like a reverse audio taper.
(http://i36.photobucket.com/albums/e16/fommof/HotPotzICAR.jpg~original) (http://s36.photobucket.com/user/fommof/media/HotPotzICAR.jpg.html)
Old thread, but I figured I'd try to offer some assistance. Rather than trying to shoehorn a compatible foot-pedal tunable pot into the phase LFO design, we can modify the LFO to work with a standard value potentiometer.
The LFO can be replaced with a Voltage Controlled (Oscillator), which works just as it's name implies. You apply a voltage to the oscillator and it...oscillates. The voltage input varies the speed. So you can use a standard voltage divider!
Now, where can we find a VCO Schematic? Synth forums? Sure. But then we've gotta modify it so that the output of the VCO matches the voltage swing of the phaser's inherent LFO. Then we've gotta remove those LFO components from the board and shoehorn this bastard in. Do you have any idea how many sleepless nights it took me to research the subject? An embarrassing amount...
Oh wait. RG Keen already did that? Without destroying the pedal's LFO? And we can add a few components to a perf/vero daughterboard to make this all work together? Awesome!
http://www.geofex.com/FX_images/p90ramp.pdf
Please note that this is for a leslie style ramp. You footswitch between 2 voltages, for 2 speeds. The 100K Pot and 100uF cap are there to slow down the transition between voltages. So don't include the switch, the second, pot, or the 100k pot and 100uF cap combo. Just have your "wah pot" voltage divider go straight to the base of that transistor.
NOTE! I believe the nom nom's LFO IC is shared with the input buffer. For this design, you cooooould replace IC with the IC that they call out in the document above, and just provide another IC to take care of the other IC required for the VCO.
Bonus points if you can figure out how to add a switch so that the wah rocker controls the sweep like a standard wah pedal, instead of just controlling the speed ;)